The AD9361 datasheet shows very good I/Q gain and phase imbalance (i.e. translates to good image rejection). Spec on phase is 0.2 deg typ. Q1) However, is that with the internal LO only?
Q2) How about when using the external LO?
My customer plans on using both the internal and external LO in his application.
There must be good LO harmonic filtering inside this device to get good I/Q imbalance over such a large frequency range.
Q3) So is this internal filtering applied on the “external LO” input path as well or will we need external filtering on the LO (to filter out harmonics) when we using an external LO to achieve these specs?
Q4) What harmonics is the external LO path sensitive to i.e. what kind of 90 deg LO path split are you using?
Q5) Is it a polyphase splitter?